Many types of springs are available for energy storage. For example, coil springs store energy by compressing a helically wound wire. Other types of conventional springs include torsion springs and torsion bars. All spring systems can be characterized by how much energy can be stored per unit volume. Another property by which springs can be characterized is by how much energy can be stored per unit mass (or weight). The performance of devices which utilize springs for energy storage can be improved by increasing the amount of energy which can be stored per unit volume and per unit mass.
A somewhat different type of torsional spring is disclosed in U.S. Pat. No. 5,020,783, entitled “Torsional Spring”, and issued Jun. 4, 1991. This patent discloses a torsional spring formed by providing an inner tube that is continuously turned back at a distal end to produce an outer coaxial tube. The tube is made of glass-fiber reinforced plastic. The free end of the inner portion of the tube is connected to one component of a device requiring some spring action and the free end of the outer portion of the tube is connected to a second component of the device. The two components of the device can then be rotated relative to each other and the tube provides some spring action. A major problem with this type of torsional spring is the difficulty in manufacturing it. A second drawback is the fact that the inner and outer portions of the tube must be a continuous formation of the same material. A further drawback is the fact that the relative rotation between the two components of the device is strictly limited to the amount of torsion or twisting that can be allowed between the inner and outer portions of the tube.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide a new and improved tubular torsion bar.
It is another object of the present invention to provide a new and improved tubular torsion bar with improved energy storage potential per unit mass and volume.
It is another object of the present invention to provide a new and improved tubular torsion bar that is simpler to manufacture and use.